Does Shell Have The Lead-Free Answer. It Looks Hopeful to Me

Shell caught many of us by surprise last winter when it quietly revealed that it had been working on a lead-free avgas formula for the past 10 years.

Shell? Really? Why was a global oil giant investing in the tiny fuel market of piston aviation gasoline?

Now that Shell has officially joined the FAA program to test potential replacement fuel formulas the company is talking more openly and in more detail. And its avgas experts are here in Oshkosh this week. I like what I heard from them.

First, I have a positive bias that I think most of us share when I learned that Rob Midgley who has led the development work is an active pilot. He owns a Pitts S2A and flies in competition. That may not make him a better chemist, but it sure proves he is one of us and shares our concern about the future of avgas and piston engine flying.

The other comforting news for me is how far along Shell is in the development process. Since 2004 the company, working at a facility in England, has created and tested more than 3,000 possible avgas formulas and now has one that is very, very close to duplicating the performance and other characteristics of 100LL.

Shell chemists were not starting from scratch because the company has been a leading supplier of very high octane motor racing fuels. Shell has fueled Formula 1 cars for years.

Shell also has a long history in aviation fuel development being the first to produce 100 octane back in the 1930s.

The lead-free formula Shell is submitting to the FAA to begin the qualification process rates comfortably above 100 octane and meets the existing ASTM D910 specification for avgas in every way except for two small details.

One of those differences is the new formula is a few degrees off in production boiling point. The other is that the energy density by volume is just under 3 percent lower. However, the energy density by mass is the same as 100LL. That means a gallon of the new stuff has about 3 percent less energy potential, but 6 pounds of the new fuel has the same energy as 6 pounds of 100LL. That is certainly a difference I can live with.

Rob and the others from Shell are not saying exactly what is in the new fuel formula other than that the components come from the same sources as other gasoline blends. There is no magic ingredient or silver bullet that does the job of lead. If such a miracle ingredient existed they wouldn’t have needed more than 3,000 different formulas to test.

Because the components of the new formula are not an exotic new chemical there is every expectation that final retail price will be similar to 100LL. At some airports you can pay more than $8 a gallon now, and at others perhaps less than $4. Shell thinks those same delivery and other cost factors will drive the final price of its new formula.

Rod rejects the term “drop-in replacement” for the new fuel because it is a different chemistry than 100LL. He prefers “transparent” meaning though the fuel makeup is different what the engine and fuel system experience with the new fuel will not change.

The new fuel is test flying in a Piper Saratoga with good results so far. But Shell plans to follow the FAA’s piston aviation fuel initiative process that should lead to a fleet wide approval of a fuel spec. The first phase now getting started tests fuels in the laboratory. Actual engine and flight testing begins early next year, and the goal is to have an approved formula by 2018.

If approved the Shell formula will become a public ASTM specification but certain production processes will be patented. A greater variety of facilities will be able to make the new fuel because the lead is gone. Shell expects to license the process to any facility that can produce the fuel in addition to its own global network of refineries.

So why is giant Shell investing so much into the little avgas market? The answer is that Shell is a global aviation fuel leader and it intends to remain so. And that means bringing along us little guys. “Over the years we have profited from avgas and now it’s time to invest in the future. That’s how business works,” Rob said. I like to hear that.

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8 Responses to Does Shell Have The Lead-Free Answer. It Looks Hopeful to Me

  1. Glenn Darr says:

    all that has to be done is get rid of the corn lobby and get ethanol out of auto gas and you have your “drop in ” replacement. And, for less cost at that!!

  2. John Lines says:

    Amen to that! if they can’t / won’t get the price down its only “half ” a favor. Press on Shell!

    • Doug D says:

      Yeah, and if they could only get the price of milk down to $1.50/gal. Given inflation the price of avgas should be $5.48/gal. Just about where it is.

  3. Ian says:

    I need some clarification : if a new lead-free fuel doesn’t have a lead substitute, what is the effect on your engine’s valve -seats? Octane value doesn’t come into that problem. I imagine Shell will have thought of that, so will the new fuel run in existing engines without additives to protect the valves? Maybe Mac, or somebody like Mike Busch, could elucidate?

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